query: Return error on unclosed tree pattern in alternation

Fixes tree-sitter#1436

Author: maxbrunsfeld

cli/src/tests/query_test.rs

@@ -78,6 +78,7 @@ fn test_query_errors_on_invalid_syntax() {
             .join("\n")
         );
 
+        // Empty tree pattern
         assert_eq!(
             Query::new(language, r#"((identifier) ()"#)
                 .unwrap_err()
@@ -88,6 +89,8 @@ fn test_query_errors_on_invalid_syntax() {
             ]
             .join("\n")
         );
+
+        // Empty alternation
         assert_eq!(
             Query::new(language, r#"((identifier) [])"#)
                 .unwrap_err()
@@ -98,6 +101,8 @@ fn test_query_errors_on_invalid_syntax() {
             ]
             .join("\n")
         );
+
+        // Unclosed sibling expression with predicate
         assert_eq!(
             Query::new(language, r#"((identifier) (#a)"#)
                 .unwrap_err()
@@ -108,6 +113,8 @@ fn test_query_errors_on_invalid_syntax() {
             ]
             .join("\n")
         );
+
+        // Unclosed predicate
         assert_eq!(
             Query::new(language, r#"((identifier) @x (#eq? @x a"#)
                 .unwrap_err()
@@ -144,6 +151,7 @@ fn test_query_errors_on_invalid_syntax() {
             .join("\n")
         );
 
+        // Unclosed alternation within a tree
         // tree-sitter/tree-sitter/issues/968
         assert_eq!(
             Query::new(get_language("c"), r#"(parameter_list [ ")" @foo)"#)
@@ -155,6 +163,22 @@ fn test_query_errors_on_invalid_syntax() {
             ]
             .join("\n")
         );
+
+        // Unclosed tree within an alternation
+        // tree-sitter/tree-sitter/issues/1436
+        assert_eq!(
+            Query::new(
+                get_language("python"),
+                r#"[(unary_operator (_) @operand) (not_operator (_) @operand]"#
+            )
+            .unwrap_err()
+            .message,
+            [
+                r#"[(unary_operator (_) @operand) (not_operator (_) @operand]"#,
+                r#"                                                         ^"#
+            ]
+            .join("\n")
+        );
     });
 }
 

lib/src/query.c

@@ -1655,11 +1655,14 @@ static TSQueryError ts_query__parse_pattern(
         is_immediate
       );
 
-      if (e == PARENT_DONE && stream->next == ']' && branch_step_indices.size > 0) {
-        stream_advance(stream);
-        break;
-      } else if (e) {
-        if (e == PARENT_DONE) e = TSQueryErrorSyntax;
+      if (e == PARENT_DONE) {
+        if (stream->next == ']' && branch_step_indices.size > 0) {
+          stream_advance(stream);
+          break;
+        }
+        e = TSQueryErrorSyntax;
+      }
+      if (e) {
         array_delete(&branch_step_indices);
         return e;
       }
@@ -1707,12 +1710,14 @@ static TSQueryError ts_query__parse_pattern(
           depth,
           child_is_immediate
         );
-        if (e == PARENT_DONE && stream->next == ')') {
-          stream_advance(stream);
-          break;
-        } else if (e) {
-          return e;
+        if (e == PARENT_DONE) {
+          if (stream->next == ')') {
+            stream_advance(stream);
+            break;
+          }
+          e = TSQueryErrorSyntax;
         }
+        if (e) return e;
 
         child_is_immediate = false;
       }
@@ -1853,28 +1858,28 @@ static TSQueryError ts_query__parse_pattern(
           depth + 1,
           child_is_immediate
         );
-        if (e == PARENT_DONE && stream->next == ')') {
-          if (child_is_immediate) {
-            if (last_child_step_index == 0) {
-              return TSQueryErrorSyntax;
+        if (e == PARENT_DONE) {
+          if (stream->next == ')') {
+            if (child_is_immediate) {
+              if (last_child_step_index == 0) return TSQueryErrorSyntax;
+              self->steps.contents[last_child_step_index].is_last_child = true;
             }
-            self->steps.contents[last_child_step_index].is_last_child = true;
-          }
 
-          if (negated_field_count) {
-            ts_query__add_negated_fields(
-              self,
-              starting_step_index,
-              negated_field_ids,
-              negated_field_count
-            );
-          }
+            if (negated_field_count) {
+              ts_query__add_negated_fields(
+                self,
+                starting_step_index,
+                negated_field_ids,
+                negated_field_count
+              );
+            }
 
-          stream_advance(stream);
-          break;
-        } else if (e) {
-          return e;
+            stream_advance(stream);
+            break;
+          }
+          e = TSQueryErrorSyntax;
         }
+        if (e) return e;
 
         last_child_step_index = step_index;
         child_is_immediate = false;